From: "H.J. Lu" <hjl.tools@gmail.com>
To: libc-alpha@sourceware.org
Cc: Noah Goldstein <goldstein.w.n@gmail.com>
Subject: [PATCH] x86-64 strncat: Properly handle the length parameter [BZ# 24097]
Date: Thu, 1 Dec 2022 16:37:11 -0800 [thread overview]
Message-ID: <20221202003711.358774-1-hjl.tools@gmail.com> (raw)
On x32, the size_t parameter may be passed in the lower 32 bits of a
64-bit register with the non-zero upper 32 bits. The string/memory
functions written in assembly can only use the lower 32 bits of a
64-bit register as length or must clear the upper 32 bits before using
the full 64-bit register for length.
This pach fixes strncat for x32. Tested on x86-64 and x32. On x86-64,
libc.so is the same with and without the fix.
---
.../x86_64/multiarch/strcat-sse2-unaligned.S | 4 ++
sysdeps/x86_64/multiarch/strncat-avx2.S | 4 ++
sysdeps/x86_64/multiarch/strncat-evex.S | 5 ++
sysdeps/x86_64/x32/Makefile | 2 +-
sysdeps/x86_64/x32/tst-size_t-strncat.c | 59 +++++++++++++++++++
5 files changed, 73 insertions(+), 1 deletion(-)
create mode 100644 sysdeps/x86_64/x32/tst-size_t-strncat.c
diff --git a/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S b/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S
index 9d2ca1d504..b0f9c5fa83 100644
--- a/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S
+++ b/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S
@@ -35,6 +35,10 @@
ENTRY (STRCAT)
mov %rdi, %r9
# ifdef USE_AS_STRNCAT
+# ifdef __ILP32__
+ /* Clear the upper 32 bits. */
+ movl %edx, %edx
+# endif
mov %rdx, %r8
# endif
diff --git a/sysdeps/x86_64/multiarch/strncat-avx2.S b/sysdeps/x86_64/multiarch/strncat-avx2.S
index ffa58bd0de..73baeee473 100644
--- a/sysdeps/x86_64/multiarch/strncat-avx2.S
+++ b/sysdeps/x86_64/multiarch/strncat-avx2.S
@@ -51,6 +51,10 @@
.section SECTION(.text), "ax", @progbits
ENTRY(STRNCAT)
+# ifdef __ILP32__
+ /* Clear the upper 32 bits. */
+ movl %edx, %edx
+# endif
/* Filter zero length strings and very long strings. Zero
length strings just return, very long strings are handled by
using the non-length variant {wcs|str}cat. */
diff --git a/sysdeps/x86_64/multiarch/strncat-evex.S b/sysdeps/x86_64/multiarch/strncat-evex.S
index bced4e8944..1ef3a22209 100644
--- a/sysdeps/x86_64/multiarch/strncat-evex.S
+++ b/sysdeps/x86_64/multiarch/strncat-evex.S
@@ -79,6 +79,11 @@
.section SECTION(.text), "ax", @progbits
ENTRY(STRNCAT)
+# ifdef __ILP32__
+ /* Clear the upper 32 bits. */
+ movl %edx, %edx
+# endif
+
movq %rdi, %rax
/* NB: It's safe to filter out zero-length strings WITHOUT
diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile
index 31732aa248..a015789a4f 100644
--- a/sysdeps/x86_64/x32/Makefile
+++ b/sysdeps/x86_64/x32/Makefile
@@ -10,7 +10,7 @@ ifeq ($(subdir),string)
tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy \
tst-size_t-memrchr tst-size_t-memset tst-size_t-strncasecmp \
tst-size_t-strncmp tst-size_t-strncpy tst-size_t-strnlen \
- tst-size_t-memcmp-2
+ tst-size_t-memcmp-2 tst-size_t-strncat
endif
ifeq ($(subdir),wcsmbs)
diff --git a/sysdeps/x86_64/x32/tst-size_t-strncat.c b/sysdeps/x86_64/x32/tst-size_t-strncat.c
new file mode 100644
index 0000000000..eda93f5af9
--- /dev/null
+++ b/sysdeps/x86_64/x32/tst-size_t-strncat.c
@@ -0,0 +1,59 @@
+/* Test strncat with size_t in the lower 32 bits of 64-bit register.
+ Copyright (C) 2022 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#define TEST_NAME "strncat"
+#include "test-size_t.h"
+
+IMPL (strncat, 1)
+
+typedef char *(*proto_t) (char *, const char*, size_t);
+
+static void *
+__attribute__ ((noinline, noclone))
+do_strncat (parameter_t a, parameter_t b)
+{
+ return CALL (&b, a.p, b.p, a.len);
+}
+
+static int
+test_main (void)
+{
+ test_init ();
+
+ parameter_t dest = { { page_size - 1 }, buf1 };
+ parameter_t src = { { 0 }, buf2 };
+
+ int ret = 0;
+ FOR_EACH_IMPL (impl, 0)
+ {
+ src.fn = impl->fn;
+ buf1[0] = '\0';
+ do_strncat (dest, src);
+ int res = strncmp (dest.p, src.p, dest.len);
+ if (res)
+ {
+ error (0, 0, "Wrong result in function %s: %i != 0",
+ impl->name, res);
+ ret = 1;
+ }
+ }
+
+ return ret ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+#include <support/test-driver.c>
--
2.38.1
next reply other threads:[~2022-12-02 0:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-02 0:37 H.J. Lu [this message]
2022-12-02 1:39 ` Noah Goldstein
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